This invention relates to a catalyst for a lower alcohol oxidation reaction such as a catalyst for a methanol oxidation reaction or the like whose active component is SbRe2O6 or other such rhenium-antimony compound oxides, and to a manufacturing method for a partial oxide of a lower alcohol such as dimethoxymethane or the like from methanol or other such lower alcohols using the catalyst for a lower alcohol oxidation reaction.
Dimethoxymethane has been conventionally manufactured by subjecting methanol and formaldehyde as materials to reaction in aqueous solution with an acidic catalyst. The examples of the acidic catalyst used in such reaction include mineral acids such as hydrochloric acid, sulfuric acid and the like, Lewis acid such as FeCl3, AlCl3 and the like, overacidic cation exchange resin, and inorganic solid acid and the like (German Patent Specification Nos. 800399, 1177126 and 1155780, Japanese Laid-Open Patent Application Nos. 47-29309 and 58-162546). However, the material formaldehyde is prepared by oxidizing methanol, so that the above-mentioned method has two-stage process wherein formaldehyde which is prepared from methanol is subjected to reaction with methanol, and it causes a problem in its productivity.
On the other hand, a method in which dimethoxymethane is directly manufactured from methanol without using formaldehyde is also known. The examples of the method include a method using a catalyst containing a copper oxide (Japanese Laid-Open Patent Application No. 5-237387), a method using a catalyst in which metal comprised of two different kinds of metal and/or compounds of these metals exist on the ion conductor (Japanese Laid-Open Patent Application No. 6-65123). However, the method for manufacturing dimethoxymethane using the former catalyst containing a copper oxide takes a long time to complete the reaction, and the yield is not necessarily satisfactory, while the method for manufacturing dimethoxymethane using the latter catalyst shows high selectivity of methyl formate, though it shows selectivity as low as 7% with regard to dimethoxymethane. Both methods have had problems to be solved in the aspect of practicability.
Dimethoxymethane is also called formaldehyde dimethyl acetal or methylal, and known as a useful compound mainly used as a material of medicines, flavorings and resin. A solid catalyst which can manufacture such useful compounds selectively and efficiently by direct methanol oxidation has not been known yet. An object of the present invention is to provide a catalyst for a lower alcohol oxidation reaction which makes possible to manufacture a partial oxide of a lower alcohol such as dimethoxymethane or the like selectively and efficiently by direct oxidation of a lower alcohol such as methanol or the like, and to a method for manufacturing a partial oxide of a lower alcohol such as dimethoxymethane or the like selectively and efficiently from a lower alcohol such as methanol or the like by using this catalyst for a lower alcohol oxidation reaction.
The inventors conducted diligent research aimed at achieving the stated object, learned that a catalyst which has SbRe2O6 or other rhenium-antimony compound oxides as active components shows excellent catalytic activity in oxidation reaction of methanol or other lower alcohol, and that dimethoxymethane or other partial oxide of a lower alcohol can be manufactured selectively and efficiently with this rhenium-antimony compound oxide catalyst, and the present invention has been completed.
Specifically, the present invention relates to a method for manufacturing a partial oxide of a lower alcohol characterized by that a lower alcohol is subjected to vapor phase contact oxidation with a molecular oxygen-containing gas in the presence of a lower alcohol oxidation reaction catalyst which has a rhenium-antimony compound oxide as its active component, a method for manufacturing a partial oxide of a lower alcohol, wherein the rhenium-antimony compound oxide is SbRe2O6, a method for manufacturing a partial oxide of a lower alcohol, wherein vapor phase contact oxidation is conducted at a temperature of 300xcx9c400xc2x0 C., a method for manufacturing a partial, oxide of a lower alcohol, wherein a lower alcohol is methanol, and a method for manufacturing a partial oxide of a lower alcohol, wherein a partial oxide of a lower alcohol is dimethoxymethane.
The present invention also relates to a catalyst for a lower alcohol oxidation reaction characterized in having a rhenium-antimony compound oxide as its active component, a catalyst for a lower alcohol oxidation reaction, wherein the rhenium-antimony compound oxide is SbRe2O6, and a catalyst for a lower alcohol oxidation reaction, wherein the lower alcohol is methanol.